Certain types of equipment used in nuclear power plants, such as switch gear motors and relays, or portions thereof, may be made from synthetic molded materials like phenolics, to which mineral or organic fillers, such as wood flour, have been added. In order to insure the integrity of nuclear reactor facilities, it is frequently necessary to know the level of radiation which will cause the electrical and/or mechanical properties of such materials to begin to deteriorate, hereinafter referred to as the radiation threshold of the material. For example, it may be necessary to know the radiation level which will begin to produce a reduction of the thermal insulation properties of the material, or a reduction in tensile strength.
In accordance with conventional techniques, radiation resistance is generally measured as a function of the deterioration from the norm of the desired properties of the material under test. Typically, samples of the material are irradiated and then subjected to physical tests. Such measurements are complicated and time consuming, and they usually require a large number of specially machined samples of the material under test. Further, a number of these tests, such as the determination of the rupture strength of the material, require samples of relatively large size which are difficult to position inside a radiation chamber for the purpose of a test. As such, the cost of such tests is often high.